Telephone-exchange system



Patented Jan. 8, 1924.

UNITED STATES PATENT m nce.

ALBEN E. LUNDELL, OF NEW YORK, N. Y.,' ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, A CORPORATION OF NEW YORK; 1

TELEPHONE-EXCHANGE SYSTEM.

Application filed November 6, 1920. Serial No. 422,256.

T 0 all whom it may concern ,Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Telephone-EX- change Systems, of which the following is a full, clear, concise, and exact description. V This invention relates to telephone ex change systems, and more particularly to systems in which a manual operator establishes connections to subscribers lines and P. B. X. trunks by means of a plug ended cord circuit. 7 V

It is the object of this invention to provide a system and apparatus such that accurate connections may be obtained quickly and as a result of a minimum number of manual operations by an operator.

More specifically, the invention isdirected to a systemin which an operator serves groups of P. B. X. trunks in addition to subscribers lines, and is of special utility when it happens that the P. B. X. trunks are arranged in groups of large capacity.

l/Vhen there are a large number of trunks in any given group the usual method of establishing connection requires that the operator test these trunks successively. Regardless of the efiiciency of the operator a considerable time interval is required in a case of a trunk group of for example, .100 to 500 trunks, and there is in addition the danger that in testing. these trunks at a high rate of speed the operator may plug in without fully receiving or noticing the busy tone.

It is a further object of the invention to provide automatically operated mechanism associated with an operators position such that when she inserts the calling plug into ajack associated with the group of trunks to which the connection is to be extended, an idle trunk will automatically be selected and the incoming end of the link circuit will be automatically extended to such trunk, and signaling current will be applied to such se lector trunk without, further attention by the operator. v

It is an additional object of, the invention to provide automatic switching means which,

will automatically operate toselect the desired group of trunks whenthe operator with a P. B. X. trunk by means of the special automatic switching equipment.

It is thought that the invention will best be understood from the following detailed description, reference being hadto the accompanying drawing. 3 j In the drawing the figure shows so much of a telephone system as is necessary to an understanding of the invention. The automatic switch, the circuits" of which are shown in the lower left-hand portion of the drawing,-is similar in mechani cal construction and method of operationto that shown in Patent No. 1,808,867, issued July8, 1919, to J. N. Reynolds. This switch has been used in order to simplify thedisclosure asmuch as possible. It is a 500 point switch arranged to have five multiple,

brushes, eachof which has accessfto ten groups of ten lines each; It will, therefore, be assumed that the operaton'whose cord circuit is indicated at O has access to fifty groups of P. ,B. X. trunks, there beingyten trunks in each group. In practice it is'de sirable to use the system in connection with trunk groups of larger ca acity. In this case, selection of agroup of trunks may be made by means of an ordinary-"two-movement stepby-step switch, and an' 'idle'tru11k may then be selected by means of a series (there being any desired number of switches in the series) of small step-by-step' switches which would be successively operated to find an idle trunk. The invention is, therefore, not to be limited to the specific embodiment shown, since this, is,'as pointed out above, merely a simplified disclosure. 1

The operation of the system in case the subscriber at substation A desires to extend the call to the substation at B, will first be described.

When the subscriber at removes his re; ceiver'frrh the 'swi tchho'olr, line relay 1 energiie'd by Iiieahs of a circuit 'eirtend'ing from grounded battery, winding or 1, back contact or cut-on" relay 2, over the loop "of the calling "sub scribers line, including the substation appa ratus, outer armature and back contact of relay 2 to ground. The energization of relay 1 causes the illumination of lainp 3.

Theoperator, whose cord circuit, a indi; cated observing the llghting olf 3;;ins i S aiiswering lug, 4 into jack 5 associated with Iaiii'p 3. A circuit is tlien tem l e ts eu de a e y, r sis ance 6,.1S eevefcontacts plug Pl and jac k 5 win m i' iito'fi' rel y v2 t gr nd- R lEi/SZ. n is zd 1. th ,c ui an a tracts it s meatless, thus c'au-siiigc the dd energization of rel ay l, whichdin m nganese pl3 to eXt-inguished, TheFA openat-q" "at 0, by f o a enin k y (P t li 11 i D- 1yfli i en fl 'li ih il 1 Show a the dead time aatbnv se w th the calling sc if iber to ascertain the. nunir tdja sfubsci'iber in a distant oflice then con; verses with the o erator at such, efii ebr an t n ci -W re;- T perator at the distant receives the nuinber of the Wanted line assigns a trunk circuit, for the ester the operator at O. The, A? operator then ins erts calling -'p;lug Tilitbttiink ad: 8, whereupon a circ uit is completed from. grounded battery, lower ri ht-hat .W irs'. 'qfg i 'p' rit fi l eg t Pr "r e r 9 ees o pl g? ania ,1we eft-h ed winding ofithe repeating coil ll, left hand of -relay ;12, upper left-hand winding of repeating coil 11, contacts of ac l; 7;, upper right-han d winding of repicatingv coil 9 to ground. Belay 12 7 is y energized inthis circuit and cornpletes a circh rom ame d d b t r l mp. mi

l'ower arn atureof re1ay14cand its back contact, conductor 15 left-hand armature and back contact of relay 59, armature and fronticontact of relay 12 to ground. Lamp 13 i slilght-ed to. inform the B. operator at that eonnection has-been extended to the trunk circuit. v '7 p When the operator at O I observes the lighting oflarnp 13 she inserts plug. 16 into multiple jack 17 associated with the desired the. wanted line isbusjgthe-operator will 'receive a click in'herheadset when tip oftheplug n ges. hefsle v 0 1- tact of jack 17, since the busy condition of the line is indicated by the presence of battery potential supplied to the sleeve contact of jack 17, in a manner to be hereinafter described. Current flowing from the battery to the sleeve contact of jack 17, tlp contact of plug 16, upper armature and back cfohta'ct of relay14, winding of induction coil 18 to ground induces a current in the 'circuitof-the operators receiver, causing a "click to inform her that line is busy.

Assuminghowever, thatthe wanted line is idle, the operator inserts plug 16 completely into jack 17 whereupon a circuit is completed from grounded battery, winding "of relay 14, sleeve contacts of plug 16 and jack 17 winding of cut-off relay 19 to ground. Relays 14 and 19 are energized in this circuit while the battery supplied to the sleeve, 'con'tact's of the other rnultiple jacks of the wanted line, will render these jack-s busy to othertesting operators. The eiie'rgi'zatio'n of "cut-"off relay19 removes the control of the called subscribers line relay in th ei, well kno wh manner; The energiza ti'on of relay 14} eateries the tip and ring conductors of the .cordeircuittothe tip and ring contacts of the plug 'a'ndvconiipletes 'at the ame ime, a. circuit from jground'edfbattery, winding of relay 20, left han'd arina ture. and back contact of relay '21, righthand armature and back contact ofri'nging relay 22, lowerin'ost armature and frontcontact of relay14, conductor 15, back contact and left-hand armature of relay 59, arr'riature and front'contact of relay 12 to ground. The relay 20 is energized 'inthis circuit. It is to beiiiot ed that the winding of relay 21 is included in a b'ranch path of the energizing circuit of relay 20, but since it is shunt-- ed by a low resistance :p a'th, relay 21 does not energize atjthi's time. u v

t It is to be observed that relay 14 upon energization, opens at Iniddle lower armature, the circuit of the supervisory lamp 13, thus allowing this larnp to be eiitini$h The energization of relay 2O completes the ringing circuit which extends from ground through a source of alternating ringing current 23, winding of relay 22, lower arinature a'nd front contact of'relay 20, inner lower armature and front contact of relay 14, ring (contacts of plug 16 and jack l' f,'.,thence through the loop of the called substation line, including the bell magnets and condensen'tip contacts ofjack 17 and plug 16, upper armature and front contact of relay l l, upper armature and front contact ofrelay 20 to ground. The current ,flpwing inthe above traced circuit causes the bell gat substation to be rung. When the subsoribe r at the substation an.- swers and rernoves his receiver from the switchhook, the resistance of the circuit is decreased sufficiently to allow marginal re-- lay 22 to operate.

The operation of relay 22 removes the shunt from about the winding of relay 21, and this relay is energized and completes a locking circuit for itself from grounded battery by way of its left-hand armature and front contact. The application of battery directly to the winding of relay 21 shunts out the winding of relay 20. Relay 20 is deenergized and connects through the righthand windings of repeating coil 11 to the tip and ring conductors respectively. Current flow through the substation of the called subscriber causes the energization of supervisory relay 24. The connection is now complete and the subscribers may converse.

When connection is no longer desired both subscribers replace their receivers. Y

Before continuing the description, it might be well to observe that the supervisory relays 10 and 7 5 in the cord circuit at were energized during talking, supervisory relay 7 having been energized over the loop of the calling line. Supervisory re lay is marginal in operation, that is,

when relay 24 is not energized and the circuit of relay 10 extends through the lefthand high resistance windingof relay 12, relay 10 cannot be energized. However, when the called subscriber answers, a parallel low resistance path is provided through the low resistance right-hand winding of relay 12, and the increased current flow which results allows relay 10 to be energized. 1

When the called subscriber replaces his receiver, supervisory relay 24 is deenergized, causing in turn the deenergization of marginal relay 10.

When the calling subscriber replaces his receiver, supervisory relay 7 5 is deenergized. The operator at 0 upon observing the light ing of the supervisory signals controlled by supervisory relays and 10, respectively, removesplugs 4 and 7 from jacks 5 and 8 respectively. Theremoval of plug 7 from jack 8, causes the deenergization of relay 12, whereupon a circuit is completed from grounded battery, lamp 13, middle lower armatureand front contact of relay 14, armature and back contact of relay 12 toground. Lamp 13 is now lighted to inform. the operator at O that connection is no longer desired, and she thereupon removes plugs 16 from jack 17. All parts of the apparatus have now beenrestored to their normal condition.

The operation of the system in case the subscriber at substation A desires to call a P. B. X. station indicated at J, will now be described. In this case the operation of this system is identical with that previously described up to the point where the operator at 0 is ready to extend the call by means of plug 16, it being remembered that she has received the designation of the wanted line by means of an order wire, and that the lighting of lamp 13 hasvindicated to her that v the call has been extended to her position.

In the present case, since the call is to be directed to a trunk in a P. B.'X'. group, the operator inserts plug 16 into jack 25, which is the jack individual to the particular group of P. B. X. trunks to which connection is to be extended' A circuit is thereupon com pleted from grounded high resistance lefthand winding of relay 26, ring conductors of jack 25 and plug 16, inner lower armature and back contact of relay 14, conductor 27, side switch arm 28 and its first contact, Winding of marginal relay 29 to grounded battery. Relay 26 is energized in this circuit, but relay 29 being marginal, does not become energized due to the presence of the high resistance left-hand winding of relay 26in its circuit. it

The impulse sending device shown in the lower right-hand portion of the drawing is constantly rotated from any desired source of power in the direction indicated by the arrow,it being understood that the impulse sending device is in the form of a cylinder which has been developed into a plane surface for thesake of disclosure. l/Vhen brush 31 engages pick-up segment 32, a circuit is completed from grounded battery, segment 32, brush 31, n'1ake-beforebreak contactsof relay 33, winding of relay 33, left-hand armature and front contact of relay 26 to ground. Relay 33 is energized in this circuit and completesa locking circuit for itself extending from grounded battery, inner left-hand armature-and front contact of re lay 33 to ground, as described. Immediately upon the energization of relay 33, marginal relay 29 becomes energized,

its circuit extending from grounded battery,

winding of relay 29, side switch arm 28 and its first contact, conductor 27, inner' lower armature and back contact of relay 14, ring contacts of plug 16 and jack 25-, right-hand low resistancewinding of relay 26, right hand armature and front'contact of relay 26, right-hand armature and front contact of relay' 33, right-hand armature and back contact of relay 34, brush 35, which is resting on a conducting portion of drum 36, to ground. The energization of relay 29 causes inturn the energization of slow-to-releasc relay 30.

As soon as brush 35 engages insulating segment 37, relay 29 is deenergized, whereupon a circuit is completed from grounded battery, winding of primary stepping magnet 38, side switch arm 39 and its first contact, winding of slow-release relay 40, inner right-hand armature and front contact of re lay 30, armature and back contact of relay 29 to ground. Primary magnet 38' is en ergized to rotate the auxiliary shaft one step. Relay 40 is energized and remains energized during the sending or" the first series of impulses. As soon-as brush engages .a conducting portion of drum threlay 29 again energized, thereby'allowing magnet 38 to complete its 'retractive movement into engagement with another tooth of the ratchet wheel which operates the auxiliary shaft oi the switch. In this manner, three impulses will be supplied to cause the switch to advance three steps in a primary or main group selecting movement.

It is to be observed that during the sending of impulses the continued energization of relay 4O maintains the circuit of escape magnet 41 by ways of side switch arm 42 and its first contact, and the front contact and armature of relay 40. As soon as brush 35 leaves insulating segment 43, at which time three impulses will have been transmitted to stepping relay 29, relay 29 will. re-

Yeti

main energized for a relatively long period, thus allowing relay to be deenergi'zed. Relay 40 upon deenergization, causes the decnergization oi escape magnet 41 which releases and advances the side switch into its second position.

When pick-up brush 47 engages conducting segment 48 of drum 49, a circuit is conpleted from grounded battery, segment 48, brush 47, make-beiorabreak contact of relay 34, winding of relay 34, lett-hand armature and front contact of relay 33 to ground. Relay, 34 is energized in this circuit and locks up by way of its left-hand armature and front contact, The energization of relay 34 extends the impulse conductor to brush 50, it being assumed that connection to a trunk in the ninth sub-group in the main group served by the third brush is desired.

The multiple connections on the leads extending from the various brushes of the impulse'r drum indicate how the impulser is connected to the relays associated with other jacks corresponding to jack 25. There is associated with each jack corresponding to jack 25 a set of relays corresponding in every way to relays 26, 33 and 34. Brushes 31and 47 are multipled to contacts 'o-lother relays 33 and 34, 'ina manner identical with that shown for the particular relays which have been disclosed. The various brushes which determine the number of impulses to be sent are connected to'the front and back contacts of the right-hand armatu'res of relays correspondingto relay 34 in such a manner that any combination of impulses required to select the particular group .01 trunks desired may be obtained.

As soon as brush 50 engages insulating segment 46 of drum 36, current flowing through relay 29 is decreased to a suiiicient extent to cause the de'energization of this re lay. Since the side switch associated with the selector is in its second position, a circuit is thereupon completed from grounded battery, winding-pt stepping magnet- 44, side switch arm 39 and itssecond contact, winding of slow-release I relay 40, inner right-hand armature and ,front contactyot relay 30, armature and back contactof relay 29 to ground. Stepping magnet, 44 and slow-release relay 40 are energized in this circuit, relay 40 causing in turn the enter; gization of escapemagnet 41. As brush 50 passes over the succeeding insulating segme'nts; relay 29 is -interrnit'tently deenergized and energized to cause the advance of the brush shaft in a sub-group selecting movement under the control of magnet44v before, relay40 remains energizedduring the sending of the series of impulses. When brush 50' leaves insulating segment .51, at which time nine impulses will have -been sent, relay 29 remains energized for ayrelatively long period oftime causing thede; energization of slowerelease relay 40, which in turn allows escape magnet 41. to ueeae gize to advance the side switch into-itsthird position. p I V As soonas the side switch reaches its third position, a circuit is completed from grounded battery, winding of test relay 52,

make-before-break contact of. such relay;

side switch arm 53, and its third contact, right-hand armature and front contact of relay 29 to ground. Belay .52is energized and locks up by way of its left-hand armature, side switch armature 54 and its third contact to ground by way otofinormalj-contact 55, which does not open until the se lected brush set has made its first-step outwardly. It is to be noted that as the'impulser continues to rotate, brush 50' will cause intermittent deenergizations of relay 29 as it engages the primary set of segments served by it. These momentary interruptions can have no ill effect at this time, how ever, since slow-release relay 40 is maintained energized to prevent the release of the side switch and since no impulses can be transmitted due to the fact that side'switch arm 39 has been advanced. to'its third position.

The energization of test relay '52 completes a circuit for side switch magnet 41,eXtending from grounded battery winding of magnet 41, inner right-hand armature and front contact of relay 52 to ground.- At the same time, a circuit is completed from grounded battery, winding'ot magnet 44, armature and back contact of magnet 44, outer right-hand armatureand front contact of. relay 52 to ground. Relay 44 is energized and causes the selected brush set to be moved into engagement with the terminals of the first idle trunk in the selected subgroup; Assuming that this trunk is busy and that busy trunks are characterizedby the presenceof groundpotential on their test terminals, relay 52' will be maintained energized irrespective of the opening of off-normal contact 55, since holding ground is now applied to test brush 56 by way of the busy 44, which interrupts its own circuit to cause such advance. When test brush 56 en'- counters the test terminal of an idletrunk, relay 52 is deenergized, thus opening the stepping circuit of magnet 44 and at thc same time allowing magnet 41 to deenergize to move the side switch into position 4.

In position 4 of the side switch, a circuit is completed from grounded battery, high resistance Winding of relay 57, side switch arm 28 and its fourth contact, conductor 27 inner lower armature and back contact of relay 14, ring conductors .of plug 16 and jack 25, left-hand high resistance winding of re lay 26 to ground. Relay 57 is energized in this circuit, but the inclusion of its high re sistance winding in the circuit of relay 26 causes relay 26 to deenergize, thus causing in turn the deenergization of relays 33 and 34.

i It is to be observed that when the side switch reaches position 4, a'circuit is ,completed from grounded battery, winding of escape magnet 41, armature and back contact of escape magnet 41, side switch arm 61 and its fourth contact, side switch arm 62 and its fourth contact, armature and. back contact of relay57 to ground. Escape magnet 41 starts to energize, but before its wind ing can be suflicientlysaturated to move its armature and the side switch controlled by its relay 57, which is a quick-acting relay, operates and removes the energizing ground from the winding of. magnet 41. w I

With relay 57- energized, energizing circuits for relays 58 and 59 are completed by way of side switch arm 60, and its fourth contact, and the armature and front contact of relay 57 to ground. I

The fenergization of relay 58 connects through the tip and ring conductors of the trunk, by way of conductors 63 and 64, to

brushes 65 and. 66 and thence over the selected trunk to the desired P. B. X. The

energization of relay 59 opens at its left-hand armature, the circuit of lamp 13 and this lamp is extinguished to inform the operator that connection has been established to the desired P. The energization of-relay 59 also completes a circuit, for supplying signalling current to the selected trunk by causing the energization of relay 2(). Relay 20 is energized over a circuit extending from grounded battery, winding of relay 20,-lefthand armature and back contactof relay '21,

right-hand armature and back contact of relay 22, outer right-hand armature and front contact of relay 59, armature and .12 and thus operate.

front contact ofrelay 12 to ground. At the same time, a circuit is'in existence for relay 21, but this relay is shunted by the direct path through the armatures and back contacts of relays 21 and 22 respectively.

Relay 20 upon energization completesa circuit from, ground, through a source of signaling current 23, Winding of relay 22, lower armature and front contact of relay 20, conductor 63, inner armature and'front contact of relay 58, brush 66, terminal 67.

and thence over the trunk conductor, through the signalling apparatus at P. B. X., C, terminal 68,- brush 65, outer armature and front contact of relay 58, conductor 64, upper armature and front contact of relay 20 to ground. When the ,P. B. X, attendant at C answers the call, the resistance of the line circuit is lowered enough to allow marginal relay 22 to be energized. Marginal relay 22 upon energization removes the shunt from about the winding'of relay 21, andrelay 21 is energized and completes a locking circuit for itself, which in turn shunts downrelay 2O as previously described. Relay 20 upon deenergization connects the tip and ring conductors from the repeating coil to conductors 63 and 64. Connection' to the wanted P. X. has now been established, it being observed that supervisory "relay 24 is energized to include the low resistance right-hand winding of relay allow supervisory relay 10 to The P. B. X. attendant willen tend the call to the desired station in theP. X., and when connection is no longer desired, the calling subscriber will replace his re 'ceiver thus causing the deenergization of relay 75 to allow the operation of the callingsupervisory signal at the 0, position.

When the P. B. X. attendant disconnects from the trunk, supervisory relay 24 will be deenergized, thus causing in turn the deenergization of supervisory relay ,10. When the operator at O notesjthat both supervisory signals are lighted, she removes plugs from jacks 5'and '8 respectively.

4 and Removal of plug 7 from ack 8 causes the deenergization of relay 12, whereupon a circuit is 1 completed from grounded battery, lamp 13, conductor 69, inner right-hand 'armatureand front contact of relay 59, armature andback contact of relay ,12 to ground." The resultant lighting of lamp 13 informs the operator at O that connection is no longerdesired and she thereupon removes plug 16 from jack 25, thus allowing relay 5.7 to be deenergized. As soon as relay 57 is deenergized a circuit is completed from grounded battery, winding of side swit'ch 'magnet '41, armature ad back contact of magnet 41, side switch arm 61 anditsfourth contact, side switch arm 62 and its fourth contact, armature and back contact of relay cause said automatic switch to select the group of trunks to which said jack is inclividual.

6. In a telephone exchange system, an operators position, groups of outgoing trunk lines, an incoming line terminating in a connecting plug, a jack individual to each group of outgoing lines, a step-by-step automatic switch associated with said incoming line, an impulse generating device common to said groups of trunk lines, and means operative upon the insertion of said plug into a desired one of said jacks to operate said automatic switch by means of im pulses supplied from said impulse generating device, to cause said automatic switch to select the group 01" trunks to which said jack is individual.

7. In a telephone exchange system, an operators position, groups of outgoing trunk lines, an incoming line terminating in a connecting plug, a jack individual to each group of outgoing lines, a step-by-step automatic switch associated with said incoming line, means associated with said jacks to supply a desired number of impulses to said automatic switch when said plug is inserted into a desired one of said jacks to cause said automatic switch to select the group of trunks to which said jack is individual, and means to select an idle trunk in the selected group.

8. In a telephone exchange system, an operators position, groups of outgoing trunk lines, an incoming line terminating in a connecting plug, a jack individual to each group of outgoing lines, a step-by-step automatic switch associated with said incoming line, an impulse generating device common to said groups of trunklines, and means operative upon the insertion of said plug into a desired one of said jacks to operate said automatic switch by means of impulses supplied from said impulse generating device to cause said automatic switch to select the group of trunks to which said jack is individual.

9. In a telephone exchange system, an operators position, outgoing trunk lines arranged in groups and sub-groups, an incoming line terminating in a connecting plug, a jack individual to each subgroup of outgoing lines, an automatic switch associated with said incoming line, and means operative upon the insertion of said plug into a desired one of said jacks to operate said automatic switch to select the sub-group of trunks to which said jack is individual.

10. In a telephone exchange system, an operators position, outgoing trunk lines arranged in groups and sub-groups, an incom ing line terminating in a connecting plug, a jack individual to each sub-group of outgoing lines, an automatic switch arranged for two directive movements associated with said incoming line, and means opera tive upon the insertion of said plug into a desired one of said jacks to operate said automatic switch in two directive move ments to select the sub-group of trunks to which said jack is individual.

11. In a telephone exchange system, an

ranged in groups and sub-groups, an incoming line terminating in a connecting plug, a jack individual to each sub-group of outgoing lines, a step-by-step automatic switch arranged for two directive movements associated with said incoming line, and means associated with said jacks tosupply two series of impulses to operate said automatic switch in two directive movements when said plug is inserted into a desired one of said jacks to cause said automatic switch to select the sub-group of trunks to which said jack is individual.

12. In a telephone exchange system, an operators position, outgoing trunk lines arranged in groups and sub-groups, an incoming line terminating in a connecting plug, a jack individual to each sub-group of outgoing lines, a step-by-step automatic switch arranged for two directive movements associated with said incoming line, an impulse generating device common to said trunk lines, and means operative upon the insertion of said plug into a desired one of said jacks to operate said automatic switch in two directive movements by means of two series of impulses supplied from said impulse generating device to cause said automatic switch to select the sub-group of trunks to which said jack is individual.

In witness whereof, I hereunto subscribe my name this 30 day of Oct. A. D., 1920.

ALBEN E. LUNDELL. 

